Terpenes, after cannabinoids, are the best-known compounds found in cannabis. Along with their potential medicinal effects, they’re primarily responsible for different aromas and flavours of can-nabis. What are the different ways growers can increase terpene levels from germination to dry-ing and curing?
If you are new to growing, or cannabis in general, terpenes are compounds that give cannabis its flavour and aroma. They are a combination of carbon and hydrogen classified by the number of isoprene units needed to build the molecule.
Not only are they responsible for the aromas and flavours of your cannabis buds, but they are thought to have numerous medicinal properties and influence the type of high that users experience. Together with cannabinoids and flavonoids, terpenes form what is called an entourage effect.
About 10-30% of cannabis resin comprises various terpenes. Some terpenes are found regularly, while others are rarely found in cannabis. The percentage of certain terpenes and the ratios in which they occur vary depending on the plant variety and environmental conditions.
Plants produce terpenes to attract pollinators, beneficial insects, and repel animals or pests from the plant. Since cannabis plants are wind-pollinated, they produce terpenes mainly to protect themselves from herbivorous animals and pests.
In cannabis plants, terpenes are formed in the resin glands called trichomes. So, in order to produce more terpenes, cannabis plants need to make more trichomes. There are many ways to help your cannabis plants produce more terpenes, and here are the most useful and common ones.
It all starts with good genetics. Even under the best conditions and with all the techniques mentioned in this article, you cannot turn ditch weed into “top-shelf” connoisseur buds. Due to the prohibition of cannabis, breeders have primarily focused on getting the highest THC content possible.
And during that time, that was a reasonable thing to do. Cannabis research was very limited, and we knew very little about other compounds found in cannabis. The pungent smell of cannabis was actually the opposite of what growers wanted. It attracted unwanted attention and increased the risk of them getting arrested.
With the (re) legalisation of cannabis, the market’s needs began to change. Consumers not only wanted the cannabis to get them high, but they also wanted it to smell and taste good. When we researched the plant more, we discovered that terpenes also have medicinal benefits and effects.
In response to market needs, growers began breeding varieties with higher levels of terpenes. If you are a medicinal user, you want to choose the varieties with the dominant terpenes that are best for your ailments. And if you are a “recreational” smoker, you want to choose the flavours and aromas you prefer. Usually, cannabis dispensaries offer terpene analysis alongside cannabinoids or list the dominant terpenes in their strains.
Throughout the European market, seed banks provide cannabis enthusiasts with the opportunity to purchase a wide variety of strains and cultivate their own world-renowned genetics with impressive terpene profiles. Here are five of our favourite cultivars with an exquisite flavour palate!
Five strains high in terpenes
1. Guava Jelly
This tropical cultivar has a terpene profile heavy in limonene and has an impressive parental linage, made of Wedding Cheesecake, Strawberry Kush, OG Kush, and Durban. Expect sweet notes of exotic fruit with a pungent, skunky undertone. Guava Jelly is available as feminized seeds, and can be purchased here!
2. Skunk #1
Bred from an array of delectable parental strains, including Acapulco Gold, Colombian Gold, and an Afghan indica. Skunk #1, is the strain that influenced all modern-day hybrids. Renowned for its pungent skunky aroma, this classic cultivar is heavy in myrcene with sharp notes of pinene, which helps bring out the iconic musky aroma! The Sensi Seeds catalogue has regular, feminized and automatic versions of Skunk #1 available for all types of cultivators.
3. Girl Scout Cookies
Created from an array of cannabis cup winners, this recent addition to the cannabis scene has a remarkable lineage of Durban, Hindu Kush, and OG Kush. Its exquisite terpene profile includes an abundance of myrcene, pinene, and linalool, which gives way to flavours of sweet sandalwood with earthy notes and a deep citrusy aroma. Girl Scout Cookies seeds are available to purchase as a feminized variety.
4. Silver Haze
This award-winning strain has been rewarding users with its deliciously sweet terpene profile combined with a soothing, uplifting high since the early 90s and has remained a fan favourite ever since. Renowned for its sweet citrus notes with heavy undertones of pine, sandalwood and citrus. Silver Haze, feminized and regular, has a magnificent terpene profile, and shouldn’t be underestimated.
A staple of the Dutch coffeeshop scene, Tangie was bred from California Orange and Skunk #1. So, as you can imagine, it has an extravagant flavour profile which is heavy in myrcene and limonene. Expect hints of freshly peeled tangerine with lemon rinds and undertones of musk.
Although you can maximise the production of terpenes in any growing system, the soil is the best and most pristine medium when it comes to terpenes. High-quality soil provides the best pH and alkalinity levels, maximises nutrient uptake, and keeps photosynthesis at optimal levels. Growing cannabis in native soil brings out the terroir of the region.
Terroir refers to the specific medium and environment in which plants are grown. It is responsible for some of the unique flavours and aromas of plants. Just as wines produced in specific regions taste different even though they are made from the same grape variety, the same is true for cannabis plants.
Soil building is a science in itself. When it comes to terpene production, you want to increase the sugar content of plants. Since plants do not take up added sugars, your plant nutrient plan should encourage plants to produce sugars independently. We’ll explain how to do this next.
3. Nutrients, additives, and boosters
Sugars or carbohydrates are essential during the flowering phase if you want big, dense buds with higher resin and terpene content. Your cannabis plants will require varying amounts of carbohydrates throughout their life cycle. Carbohydrates have the most significant impact during the bud ripening phase.
Many of the flavour-enhancing nutrients and additives are carbohydrate-based. This means that they add sugars to the root zone to promote microbial populations. In turn, this gives the plants access to more sugar or nutrition.
There are also nutrient supplements that are a little more specific to terpene production than carbohydrate-based supplements. They use naturally occurring plant compounds known as bio-osmotic potentiators that stimulate plants to increase their production of terpenes and essential oils.
Bacteria often get a bad reputation. However, as we now know more about the microbiome and probiotics, we are beginning to appreciate the benefits. When you add Lactic Acid Bacteria (LAB) to your soil, this special microbe will convert sugars into short-chain fatty acids. Your plant will use these to produce more trichomes, cannabinoids, and terpenes.
Using black grape molasses, whether in the soil or in your watering mix, will encourage microbial life in the root zone. Adding molasses ensures that they can do their best to allow plants’ faster and more efficient uptake of nutrients.
Efficient use of nutrients leads to increased trichome production, higher yields, and overall healthier plants. When using molasses in your irrigation solution, mix two tablespoons into five litres of lukewarm water.
The addition of amino acids such as fulvic acid and humic acid encourages chlorophyll formation and improves nutrient uptake. This, in turn, increases the plant’s ability to synthesise a greater amount of sugars present in its metabolism, enhances the absorption of nutrients, and increases the terpene content in your plants.
Many growers have been successful in increasing terpene content by using seaweed extracts. Marine algae extracts increase the bioavailability of micro-nutrients. They also contain natural growth hormones that stimulate plant cell division. When applied to the plant’s root zone, seaweed extracts trigger the development of heavier and more pronounced roots. More extensive and thicker roots allow the plant to absorb more water and nutrients, increase carbohydrate production, and increase terpene content.
Keep in mind that the plant’s needs change during the life cycle. During the last two weeks, nitrogen should be eliminated, as excess nitrates burn carbohydrates and waste energy. This slows the growth and reduces terpene production. Potassium levels, however, should be increased during the flowering stage as it causes sugar levels in the plant to rise.
Cannabis plants produce trichomes as a defensive response to various attacks and stresses. The natural function of the trichome glands is essentially to protect the plant and its developing seeds from extreme conditions such as UV rays, cold weather, pests, and diseases.
Growers can use this to their advantage. By causing light stress during flowering, they can get the plants to produce more trichomes and, thus, more cannabinoids and terpenes. However, too much stress is too harmful to plants and will bring photosynthesis to a halt. As such, these techniques don’t function well on autoflowering plants, due to their ability to complete the grow cycle in as little as 12 to 13 weeks; any extra stress could be detrimental and lead to a poor harvest.
Cold weather, which is a significant stress on the plant, triggers changes in the plant’s metabolism. When this occurs in the final flowering stage, resin production increases in exchange for very little yield loss.
You should gradually lower temperatures by about 5 °C during the last two weeks of flowering. This simulates autumn conditions and signals to the plant that frost and winter are imminent. The plant will respond by putting the remaining energy into producing more resin to protect its progeny.
At this point, the buds are fully grown and just need to mature. This results in much greater and higher quality resin coverage and terpene content. Lowering temperatures in the latter stages of flowering can also speed up the flowering period and allow for a quicker harvest.
The optimal humidity for flowering cannabis is 50-60%. Lowering the humidity to 30% will slightly stress the plants, and terpene production will increase. This can be achieved by adding more fans or a dehumidifier to your environment. Lower humidity will also help reduce the risk of mould and mildew.
When you water less and less frequently, you are simulating a drought. As with any stress, the plant’s natural response is to protect itself and its seeds. By coating the flowers and seeds with more resin, plants trap moisture and protect them from lack of water.
Letting the growing medium dry out slightly will increase the cannabinoid and terpene content. It also ensures that the roots get more oxygen and boost photosynthesis.
Defoliation is the most common and popular method to boost sugar production and naturally increase terpene and cannabinoid content. Trimming the leaves increases the terpene levels by redirecting energy to the buds.
Simply cut off the young foliage as it grows. Be careful not to overdo it, though, because removing too much foliage will stunt your plants and slow down photosynthesis. Extreme defoliation will also result in lower yields and poorer quality of your buds.
Remember that the leaves are one of the most important factors in sugar production. The top leaves catch the most sunlight. So only remove them if they are blocking most of the developing buds.
There are different opinions among growers when it comes to defoliation. But if done correctly, it can increase the yield, terpenes, and cannabinoid content of your plants.
“Lollipopping” is nothing more than defoliation, just on a larger scale. The goal is to remove the bottom quarter or third of the plant. The lower branches are exposed to less light anyway, and the buds formed there will always be smaller and of lower quality than the upper colas.
Removing them at the beginning of the flowering stage will ensure that the energy produced by the plant goes to the remaining parts of the plant. This will increase not only your yields but also the overall quality of the buds.
“Super cropping” is a high-stress cultivation technique. It involves simply pinching and bending the stems and branches. Damaging the inner fibres and leaving the outer sheath intact promotes both more vigorous growth and bud development, as well as increased production of cannabinoids and terpenes.
After the plants have recovered, you will notice an “ankle” forming at this point. A bigger surface of the ankle will help the plant absorb more nutrients and transport them to the buds that are forming.
The best time to Super Crop is during the late vegetative stage and the first two weeks of flowering. If you start Super Cropping a week before flowering, the plants will have plenty of time to recover. Doing this around the second week of flowering will help with the “stretch” and spread the branches more evenly. But it will also help position the branches and buds and expose them to more light.
Flush with ice
Flushing is when the plant is watered with pure water without nutrients, and during the last weeks of harvest, some growers like to perform the final flush with ice.
Not only does this flush away stored nutrients, but it also adds stress to the plant. As a natural reaction to any pressure, the plant produces more trichomes and resin throughout the last days of flowering.
Split the stem
Although some growers like to use this technique in the last days of flowering, this method is not recommended, especially for new growers. Theoretically, splitting the stem will cause a hormonal change in your plants due to extreme stress. The plants will stop producing buds, but the resin production and cannabinoid and terpene levels will increase.
We do not recommend this method as you can cause an infection that can bring various diseases and lead to the loss of the plant. If you are not careful, you can also cut the plant completely, resulting in a premature harvest.
5. Companion planting
Companion planting is common in many agricultural crops and integrated pest management systems. It is a method in which farmers use different plants to support their main crop. By planting certain crops next to each other, they work together to improve the production and quality of their produce.
They usually do this to attract pollinators and beneficial insects, keep pests away, add nutrients to the soil, or draw minerals from the ground. Some plants have been shown to increase the levels of essential oils and sugars in neighbouring plants.
Some plants known to increase essential oil production and improve flavour are nettle, yarrow, basil, chives, and tarragon.
Lighting plays a crucial role in the entire growing process. It ensures that your plants develop properly, increases yield, and the overall quality of your buds. Different lighting and light spectrum cause (slightly) different terpenes or even terpene profiles. The same strain grown outdoors under the sun will have a somewhat diverse chemical profile than the one grown indoors under HPS or LED lights.
When it comes to terpenes, two types of light spectrum play a particularly important role. If you eliminate the red spectrum in the last 72 hours of growth, the plant will continue to synthesize terpenes, but they will not be released. This causes the terpenes to accumulate in the maturing buds.
The second important light spectrum is UV-B. As we mentioned earlier, one of the reasons why cannabis plants produce trichomes is to protect the plant from harmful UV rays. However, this can be used to your advantage. If you use a UV-B light in your environment, you can get your plant to produce more trichomes and therefore more terpenes. Adding 10-20W of UV-B light per square metre for the last 2-3 weeks will increase the terpenes in your buds.
HPS bulbs already emit a large infrared peak between 800 nm and 900 nm and do not require an additional UV-B source. If you are growing outdoors, make sure your buds are spaced correctly, so they all get enough light.
7. Reduce the CO2 levels
During photosynthesis, plants take in water and carbon dioxide (CO2) and convert them into oxygen and glucose (sugar). Many growers introduce additional CO2 into their growing environment to speed up and increase this process.
The most suitable time is during the first two to three weeks of flowering. By the end of the flowering period, the plants have formed their buds. The only thing left to do is to let these buds fully mature.
Lowering the CO2 levels in the atmosphere causes plants to produce more ethylene. Ethylene is a hormone that is essential to the ripening process. Increasing ethylene production stimulates the trichomes to put more energy into resin secretion and thus increases the terpene levels.
As your plants grow, they need nutrients to build up their leaves, stems, branches, and buds. Nutrients are absorbed from the growing medium through the roots and stored in the leaves and buds. When your plants have reached their final stage, you should stop feeding them.
Usually, growers tend to give their plants pure water during the last two weeks. This ensures that all the excess nutrients that the plant does not need or can’t use are flushed out. The leftover nutrients can leave an unpleasant taste and aroma and cause your buds to burn unevenly. Clean, flushed buds leave a pleasant, natural, aromatic end product.
To get the most out of flushing, growers can rinse their soil with 3-5 times the amount of pure water equal to the volume of dirt in the container. So, if your container holds 5 litres, you would use 15-25 litres to flush. Unlike watering your plants with just water for the last two weeks, this will ensure that any remaining nutrients are flushed out of the soil as well. When you do this, let the dry soil well and continue to water your plants with pure water.
9. Harvest at the right time
Knowing when to harvest is especially important, and the same goes for terpenes. As plants mature, their smell becomes more intense and sometimes even changes. As with cannabinoids, the best time to harvest your plants is when the trichomes start to turn amber.
If you harvest too early, your buds will have fewer trichomes and therefore fewer cannabinoids and terpenes. If you harvest too late, the trichomes will break down, and you will start to lose both your terpenes and cannabinoids.
Choosing the right time of day
Plants produce terpenes all the time, but they evaporate under the pressure of (sun)light and rising temperatures. Terpene levels increase during darkness and peak just before sunrise. During the day, terpenes evaporate and fill the surrounding air with odour to warn predators and pests. This means that plants have more terpenes at the end of darkness than after a full day of light, and at dusk, the terpene content is at its lowest.
So, the best time to harvest your plants would be just before sunrise outdoors or just before the light cycle begins indoors. Some growers even like to leave the plants in the dark for 24 or 48 hours before harvesting. This ensures that the terpene content is at its highest.
10. Drying and curing
Proper drying of your buds is a crucial point in any grow and can make the difference between a great crop and an inferior one. Since they are often in a hurry to taste the fruits of their labour, they speed up the process. To dry your cannabis buds properly, you need a dark place, a constant humidity of 45-55% and a temperature between 20-22 °C.
A steady and slow process will ensure that you preserve the terpenes and cannabinoids of your buds. The slower the drying process, the better. A proper drying process usually takes around 2-3 weeks, depending on your drying method.
After you have dried your buds, they need to cure. Curing is just a continuation of the drying process, which takes anywhere from 4-5 weeks to a few months. Some changes, like the conversion of THC to CBN, will take place, but when it comes to terpenes, a longer curing time is better.
In the first few weeks, the levels of cannabinoids and terpenes will decrease. After a few weeks, these levels will start to increase. Usually, around week eight, the terpenes are at their lowest during the curing process.
But after the 8th week, they begin to rise again, even above the levels of the freshly cut plant. Depending on the atmosphere in which the buds are stored, i.e., air, vacuum, N2, argon, or CO2, you may even see an increase of up to 20%. If you speed up the drying and ripening process, there is a good chance that your buds will have the aroma and taste of hay or chlorophyll.
Terpenes, as well as cannabinoids, are produced in the trichomes, or the plant’s resin glands. Cannabis plants produce trichomes in response to stress and environmental conditions. Stressing the plants just enough and providing them with optimal growing conditions will help produce more trichomes and terpenes. Once carefully dried and cured, buds will be fresh, fragrant, and tasty.
If you’ve had any encouraging interactions by increasing terpene levels in your plants, or if you would like to share your own experiences with terepens and cannabis, please let us know in the comments below!
Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.